Array within a structure in Extra Basic

Question

I need to define an array within a structure. I tried "Txt As Variant" and "txt() As Variant" and neither work when try to use Struct.Txt as an array. What is the correct way to define an array within a structure in Extra Basic? It works in VB but not Extra. Please point me in the right direction. 
 ' Example Data
Type RWText
 Cmd As String
 FnameA As String
 FnameB As String
 Value As Integer
 Txt As Variant
 Src As String
 Dst As String
End Type

Dim Struct As RWText
Struct.Txt(1) = "test"

Tom Fitzgibbon · Accepted Answer

Hi David, Not wanting to come across the wrong way here, but I don't like that idea at all. If I was in your shoes I would look to perform your file operations using the Microsoft.Scripting.Runtime library's FileSystemObject object. That should allow you to perform most of the various operations in one line of code. Writing to file may take some extra effort. Unfortunately as ebedit.exe doesn't have any usable intelisense or object browser, normally when I'm looking to use COM/OLE objects from other libraries I employ VBA to allow me to browse the objects and get the values for constants etc. I just add the relevant reference in the VBA project and boom. Then in my Extra! BAsic macro I just dim everything as a generic Object and replace and constants used in the code to the value of the constant as retrieved from VBA. e.g. Here is a function to write to file, it will create the file it it doesn't exist and will append to file if it does exist. 
 Declare Function myWriteToFile(TempFile as String, Overwrite as Integer, myText as String) as Integer

Sub Main
'Extra! objects
Dim mySystem as Object, mySession as Object, myScreen as Object

'File related variables
Dim Overwrite as Integer, TempFile as String, retC as Integer

'Create the Extra! objects
Set mySystem = CreateObject("EXTRA.System")
Set mySession = mySystem.ActiveSession
Set myScreen = mySession.Screen

'*** get the string we want to write to file
'Get the screen into a string
myScreenText = ""
i = 1
For i = 1 to 24
myScreenText = MyScreenText & myScreen.GetString (i,1,80) & Chr$(13) & Chr$(10)
Next i

'*** Get this string to disk !!!
'Set tempFile name
TempFile = "c:	emp\HelloWorld.David"
'Overwite my file if is exists
Overwrite = 0

retC = myWriteToFile(TempFile, Overwrite, myScreenText)

'*** Check the Return Code
If retC = 1 then
Msgbox "File Created"
ElseIf retC = 2 then
Msgbox "Text appended to existing file"
Else
Msgbox "Text not saved to file"
End If
End Sub

Function myWriteToFile(TempFile as String, Overwrite as Integer, myText as String) as Integer
'Create File related objects
Dim myFSO as Object, myFile as Object

'Create the FileSystemObject object
Set myFSO = CreateObject("Scripting.FileSystemObject")

'Check if file does not exist or we want to overwrite
If (myFSO.FileExists(TempFile) = 0 or Overwrite = -1) then
Set myFile = myFSO.CreateTextFile(TempFile)

'Write the screen to file
myFile.WriteLine myText
myFile.Close
myWriteToFile = 1
'If files exist and Overwrite is 0, then append
ElseIf (myFSO.FileExists(TempFile) = -1 and Overwrite = 0) then
Set myFile = myFSO.OpenTextFile(TempFile, 8, True, 0)
myFile.WriteLine myText
myWriteToFile = 2
Else
myWriteToFile = 0
End If
End Function Note: The above will add a blank line between writes, if you don't want the blank file, then use myFile.Write mystring, and you can control the trailing CRFL while you build the string you want to write to file. Using an array to store the file data is IMHO a bad idea, populating the array and parsing the array is expensive. How will you know the size of the array starting off, if you have to redim preserve it then it becomes very expensive. If you are writing to disk in a loop while indexing through the array then it's even more expensive. Here is a screenshot of the FSO object methods, as you can see, almost all one-line calls, so little point in creating a function to handle everything, because if just adds to volume of code you have to maintain. Another thing to watch out for when using external objects is the variable types, e.g. Extra! Basic doesn't do Boolean, so just declare as integer. In general -1 == true and 0 == false, however at one point Windows was returning true as 1, so to be on the safe side if you encounter a Boolean, check if it's 0, if it is not then it's true !! :-) Similar with TextStream, I just using String, I think the max length for a string is 65K bytes, so if you are reading or writing anything longer you may be out of luck. If you do go this route, you will likely need a second function myReadFile, so you can check if it exists and return the contents as a string.

andree · Answer

Hi David; something like below sample ? The code declares a custom data type named "Employee". It has three fields: name, id and salary. Each field is of a specific data type (string, integer and single precision floating point).n the Main subroutine, an array of type "Employee" is declared with 4 elements, called "employees". The first two elements of the array are then populated with employee data (name, id, and salary). 
 Finally, the values of the first two elements of the "employees" array are printed to the screen. 
 TYPE Employee name AS STRING * 20 id AS INTEGER salary AS SINGLE END TYPE 
 Sub Main 
 DIM employees(4) AS Employee 
 employees(0).name = "John Doe" employees(0).id = 12345 employees(0).salary = 55000.0 
 employees(1).name = "Jane Doe" employees(1).id = 12346 employees(1).salary = 60000.0 
 PRINT employees(0).name, employees(0).id, employees(0).salary PRINT employees(1).name, employees(1).id, employees(1).salary 
 End Su b

cheers

Tom Fitzgibbon · Answer

Hi David,

in terms of intelisense, you could use VB6 or a newer Visual Studio.

As for books, invariably if I can't copy and paste it, it sounds like a lot of work :-)..

e.g. searching on Google for
VBA File object
gives several relevant results.

Tom

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